MORPHOLOGICAL INSTABILITY IN INAS GASB HETEROSTRUCTURES/

Using transmission electron microscopy, reflection electron microscopy , and atomic force microscopy, we have examined InAs layers grown on ( 1 0 0)GaSb using molecular beam epitaxy at temperatures ranging from 4 00 to 500 degrees C and at growth rates ranging from 0.03 to 0.09 mono layers/s. We have found that for lower growth rates and higher tempera tures, nominally 8 monolayer InAs layers experience long-wavelength (> 100 nm) small amplitude (similar to 1 nm) surface undulations. From li near stability theory, we find that the appearance of these undulation s is consistent with large cation surface diffusion lengths that have been measured by other researchers using scanning reflection high-ener gy electron diffraction. It also appears, however, that there is no ki netic critical thickness for morphological instability of the InAs lay er. (C) 1998 Elsevier Science B.V. All rights reserved.